Characterization of cellular and vascular changes in equine follicles during hCG-induced ovulation.
Abstract: In contrast to other species, the histology of the equine follicle during ovulation has not been described. Preovulatory follicles were isolated during oestrus at 0, 12, 24, 30, 33, 36 and 39 h (n = 5-6 follicles per time point) after an ovulatory dose of hCG to characterize the cellular and vascular changes associated with ovulation in mares. Pieces of follicle wall were formalin-fixed and processed for light microscopy to evaluate the general follicular morphology and quantify selected parameters. Marked changes were observed in the histology of equine follicles in the hours before ovulation. The thickness of the granulosa cell layer doubled between 0 and 39 h after hCG (77.8 +/- 4.8 versus 158.8 +/- 4.8 microns, respectively; P < 0.01). This expansion was caused primarily by a pronounced accumulation of acid mucosubstances between granulosa cells, which was first detected at 12 h after hCG and peaked at 36-39 h. In contrast, a significant thinning of the theca interna was observed after hCG treatment. Fewer cell layers were present; theca interna cells appeared smaller than before hCG; and the presence of occasional pyknotic cells was noted at 36 and 39 h after hCG. In addition, the theca layers were invaded by numerous eosinophils. No eosinophils were observed in preovulatory follicles isolated between 0 and 24 h after hCG, but the number increased to 14.0 +/- 0.8 and 5.6 +/- 0.3 eosinophils per field (x 400) in theca interna and theca externa, respectively, 39 h after hCG treatment (P < 0.01). Severe oedema, hyperaemia and haemorrhages, and significant increases in the number of blood vessels in theca interna and externa were observed at 33, 36 and 39 h after hCG. This study provides the first in-depth characterization of the sequential cellular and vascular changes that occur in equine follicles before ovulation.
Publication Date: 2000-01-25 PubMed ID: 10645252DOI: 10.1530/jrf.0.1170115Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research article characterizes the cellular and vascular changes that occur in horse follicles during ovulation induced by human chorionic gonadotropin (hCG).
Objective of the Research
- The main aim of this study was to provide an in-depth understanding of the cellular and vascular changes within the follicles of horses during hCG-induced ovulation, which had not been described prior.
Methodology
- This study used preovulatory follicles isolated from horses during oestrus (period of sexual receptivity in mares) at different time intervals after hCG administration.
- Sections of the follicle wall were fixed and processed for light microscopy to analyze the general morphology and quantify selected parameters.
Findings
- The study found significant changes in the thickness of the granulosa cell layer, a part of the follicle, from 0 to 39 hours after hCG administration. The thickness approximately doubled due to the accumulation of acid mucosubstances between granulosa cells.
- Conversely, the theca interna, another layer of the follicle, significantly thinned after hCG treatment. Theca interna cells were observed to be smaller post-hCG treatment and occasional pyknotic cells were noticed 36 and 39 hours after hCG administration.
- The research also noted the presence of numerous eosinophils in the theca layers post-hCG administration. No eosinophils were observed in preovulatory follicles isolated in the initial 24 hours post-hCG but increased significantly by 39 hours post-hCG.
- Signs of extreme physiological responses such as severe edema (swelling caused by fluid accumulation), hyperaemia (increased blood flow to different tissues), haemorrhages (bleeding or blood spill), and significant increases in the number of blood vessels in theca interna and externa were noted approximately 33 to 39 hours after hCG administration.
Significance of the Study
- The study provides valuable insights on the sequential cellular and vascular changes occurring within equine follicles during ovulation. The results have implications for understanding the complex biological changes during mare ovulation and could potentially contribute to improving fertility treatments in horses.
Cite This Article
APA
Kerban A, Doré M, Sirois J.
(2000).
Characterization of cellular and vascular changes in equine follicles during hCG-induced ovulation.
J Reprod Fertil, 117(1), 115-123.
https://doi.org/10.1530/jrf.0.1170115 Publication
Researcher Affiliations
- Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.
MeSH Terms
- Analysis of Variance
- Animals
- Cell Count
- Chorionic Gonadotropin / pharmacology
- Edema / chemically induced
- Eosinophils / cytology
- Eosinophils / physiology
- Female
- Granulosa Cells / drug effects
- Hemorrhage / chemically induced
- Horses
- Ovarian Follicle / anatomy & histology
- Ovarian Follicle / blood supply
- Ovarian Follicle / cytology
- Ovariectomy
- Ovulation
- Ovulation Induction
- Theca Cells / drug effects
- Time Factors
Citations
This article has been cited 5 times.- Bottrel M, Ortiz I, Hidalgo M, Díaz-Jiménez M, Pereira B, Consuegra C, Yousef MS, Dorado J. Hormonal Management for the Induction of Luteolysis and Ovulation in Andalusian Jennies: Effect on Reproductive Performance, Embryo Quality and Recovery Rate.. Animals (Basel) 2022 Jan 8;12(2).
- Duffy DM, Ko C, Jo M, Brannstrom M, Curry TE. Ovulation: Parallels With Inflammatory Processes.. Endocr Rev 2019 Apr 1;40(2):369-416.
- Ishak GM, Bashir ST, Dutra GA, Gastal GDA, Gastal MO, Cavinder CA, Feugang JM, Gastal EL. In vivo antral follicle wall biopsy: a new research technique to study ovarian function at the cellular and molecular levels.. Reprod Biol Endocrinol 2018 Jul 28;16(1):71.
- Townson DH, Liptak AR. Chemokines in the corpus luteum: implications of leukocyte chemotaxis.. Reprod Biol Endocrinol 2003 Nov 10;1:94.
- Chaffin CL, Stouffer RL. Local role of progesterone in the ovary during the periovulatory interval.. Rev Endocr Metab Disord 2002 Jan;3(1):65-72.
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